Oligohydramnios

Oligohydramnios
Roya Sohaey, MD
DIFFERENTIAL DIAGNOSIS
Common
  • Preterm Premature Rupture of Membranes (PPROM)
  • Intrauterine Growth Restriction (IUGR)
  • Bilateral Renal Anomaly
    • Renal Agenesis
    • Ureteropelvic Junction Obstruction (UPJ)
    • Multicystic Dysplastic Kidney (MCDK)
    • Autosomal Recessive Polycystic Kidney Disease
  • Bladder Outlet Obstruction
    • Posterior Urethral Valves
    • Urethral Atresia
Less Common
  • Twin-Twin Transfusion Syndrome
Rare but Important
  • Prune Belly Syndrome
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
  • Diagnosis of oligohydramnios
    • Subjective
      • ↓ Pockets of fluid
      • Fetus:fluid ratio > 1:1
    • Objective
      • Maximum vertical pocket is ↓ 2 cm
      • Amniotic fluid index < 5 cm
Helpful Clues for Common Diagnoses
  • Preterm Premature Rupture of Membranes (PPROM)
    • Clinical diagnosis
    • Etiology
      • Spontaneous
      • Infection
      • Post-amniocentesis
    • Worse prognosis if PPROM early or prolonged
      • Early: PPROM < 25 weeks
      • Prolonged: PPROM > 14 days
  • Intrauterine Growth Restriction (IUGR)
    • Estimated fetal weight < 10th percentile
    • Oligohydramnios often earliest finding
    • Causes
      • Placental insufficiency
      • Fetal aneuploidy/syndrome
    • Doppler assessment
      • ↑ Umbilical artery resistance
      • ↑ Uterine artery resistance
      • ↓ Middle cerebral artery resistance
  • Renal Agenesis
    • Ultrasound findings
      • Anhydramnios (no fluid)
      • Absent kidneys and bladder
      • No renal arteries (color Doppler)
      • Clubfeet, other joint contractures
    • Pitfalls
      • May have normal fluid early (< 17 weeks)
      • Bladder secretions may mimic urine
      • Adrenal gland may mimic kidney
      • Bowel in renal fossa may mimic kidney
    • Fatal prognosis
      • Pulmonary hypoplasia
  • Ureteropelvic Junction Obstruction (UPJ)
    • Ultrasound findings
      • ↑ Renal pelvis is hallmark finding
      • Renal pelvis ≥ 7 mm after 33 weeks
      • Associated caliectasis
      • No distended ureter or bladder
    • Evaluate contralateral kidney
      • Bilateral UPJ in 10%
      • UPJ + contralateral renal anomaly in 25%
    • Prognosis
      • Depends on severity of obstruction
      • Early oligohydramnios image pulmonary hypoplasia
      • Post-obstructive cystic dysplasia
  • Multicystic Dysplastic Kidney (MCDK)
    • Renal tissue replaced by cysts
    • Ultrasound findings
      • Multiple variable-sized cysts
      • Kidney may lose reniform shape
      • ↑ Renal size initially, then ↓
      • Severe oligohydramnios if bilateral
    • 20% of MCDK are bilateral (anhydramnios)
    • 40% have contralateral renal anomaly
    • Poor prognosis if bilateral anomalies
  • Autosomal Recessive Polycystic Kidney Disease
    • Single gene disorder
      • Distal tubule/collecting duct dilatation
    • Ultrasound findings
      • Enlarging echogenic kidneys
      • Majority detected > 24 weeks
      • Macrocysts rarely seen
      • Variable oligohydramnios
    • Perinatal, neonatal, infantile and juvenile presentations
      • Perinatal form with 30-50% mortality
      • Severe oligohydramnios image pulmonary hypoplasia
      • Hepatic fibrosis (rarely in utero)
  • Posterior Urethral Valves
    • Partial or complete obstruction
    • “Keyhole” appearance
      • ↑ Bladder + ↑ posterior urethra
    • Variable hydronephrosis/hydroureter
      • ± Post-obstructive renal cystic dysplasia
    • Spontaneous decompression may occur
      • Bladder rupture image urinary ascites
      • Renal fornix rupture image urinoma
    • In-utero treatment if severe oligohydramnios
      • Serial bladder drainage
      • Vesicoamniotic shunt
    • In female fetuses, consider urethral atresia
Aug 10, 2016 | Posted by in OBSTETRICS | Comments Off on Oligohydramnios

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